Implement a CPU backend using POCL

[vchuravy]

TODO:

• Assert that POCL supports SVM system
• Support gpu_report_exception

[github-actions]

Benchmark Results

	main	1961a4b...	main/1961a4bbb920db...
saxpy/default/Float16/1024	0.739 ± 0.0074 μs	0.749 ± 0.0078 μs	0.986
saxpy/default/Float16/1048576	0.173 ± 0.0066 ms	0.178 ± 0.01 ms	0.97
saxpy/default/Float16/16384	3.34 ± 0.021 μs	3.35 ± 0.034 μs	0.998
saxpy/default/Float16/2048	0.914 ± 0.0096 μs	0.929 ± 0.012 μs	0.984
saxpy/default/Float16/256	0.593 ± 0.0055 μs	0.601 ± 0.0063 μs	0.986
saxpy/default/Float16/262144	0.0441 ± 0.00064 ms	0.0448 ± 0.0017 ms	0.984
saxpy/default/Float16/32768	6.01 ± 0.044 μs	6.02 ± 0.059 μs	0.997
saxpy/default/Float16/4096	1.31 ± 0.027 μs	1.31 ± 0.025 μs	0.999
saxpy/default/Float16/512	0.651 ± 0.0062 μs	0.662 ± 0.0068 μs	0.983
saxpy/default/Float16/64	0.558 ± 0.0046 μs	0.57 ± 0.0064 μs	0.979
saxpy/default/Float16/65536	11.6 ± 0.09 μs	11.7 ± 0.2 μs	0.992
saxpy/default/Float32/1024	0.638 ± 0.011 μs	0.637 ± 0.0096 μs	1
saxpy/default/Float32/1048576	0.232 ± 0.018 ms	0.215 ± 0.033 ms	1.08
saxpy/default/Float32/16384	2.79 ± 0.15 μs	2.82 ± 0.24 μs	0.99
saxpy/default/Float32/2048	0.761 ± 0.061 μs	0.76 ± 0.058 μs	1
saxpy/default/Float32/256	0.569 ± 0.0058 μs	0.572 ± 0.008 μs	0.996
saxpy/default/Float32/262144	0.0568 ± 0.0037 ms	0.0457 ± 0.005 ms	1.24
saxpy/default/Float32/32768	5.32 ± 0.33 μs	5.39 ± 0.65 μs	0.987
saxpy/default/Float32/4096	1.14 ± 0.089 μs	1.14 ± 0.084 μs	1
saxpy/default/Float32/512	0.604 ± 0.0074 μs	0.602 ± 0.0073 μs	1
saxpy/default/Float32/64	0.559 ± 0.005 μs	0.562 ± 0.0058 μs	0.995
saxpy/default/Float32/65536	13 ± 1.3 μs	12.2 ± 1.4 μs	1.07
saxpy/default/Float64/1024	0.759 ± 0.063 μs	0.768 ± 0.044 μs	0.989
saxpy/default/Float64/1048576	0.484 ± 0.045 ms	0.522 ± 0.051 ms	0.927
saxpy/default/Float64/16384	5.27 ± 0.28 μs	5.31 ± 0.54 μs	0.993
saxpy/default/Float64/2048	1.14 ± 0.084 μs	1.14 ± 0.086 μs	0.997
saxpy/default/Float64/256	0.588 ± 0.008 μs	0.588 ± 0.0071 μs	0.999
saxpy/default/Float64/262144	0.0958 ± 0.015 ms	0.0986 ± 0.015 ms	0.972
saxpy/default/Float64/32768	11.9 ± 0.96 μs	12.3 ± 1.5 μs	0.963
saxpy/default/Float64/4096	1.7 ± 0.2 μs	1.7 ± 0.12 μs	1
saxpy/default/Float64/512	0.642 ± 0.012 μs	0.636 ± 0.01 μs	1.01
saxpy/default/Float64/64	0.561 ± 0.0068 μs	0.565 ± 0.0058 μs	0.992
saxpy/default/Float64/65536	27.1 ± 4.8 μs	24.7 ± 3.2 μs	1.1
saxpy/static workgroup=(1024,)/Float16/1024	2.21 ± 0.028 μs	2.22 ± 0.033 μs	0.994
saxpy/static workgroup=(1024,)/Float16/1048576	0.158 ± 0.0078 ms	0.165 ± 0.012 ms	0.957
saxpy/static workgroup=(1024,)/Float16/16384	4.41 ± 0.086 μs	4.47 ± 0.13 μs	0.987
saxpy/static workgroup=(1024,)/Float16/2048	2.37 ± 0.029 μs	2.39 ± 0.031 μs	0.992
saxpy/static workgroup=(1024,)/Float16/256	2.83 ± 0.036 μs	2.87 ± 0.048 μs	0.988
saxpy/static workgroup=(1024,)/Float16/262144	0.042 ± 0.0012 ms	0.0427 ± 0.0019 ms	0.985
saxpy/static workgroup=(1024,)/Float16/32768	6.84 ± 0.18 μs	6.93 ± 0.25 μs	0.988
saxpy/static workgroup=(1024,)/Float16/4096	2.67 ± 0.037 μs	2.71 ± 0.041 μs	0.985
saxpy/static workgroup=(1024,)/Float16/512	3.28 ± 0.04 μs	3.33 ± 0.24 μs	0.986
saxpy/static workgroup=(1024,)/Float16/64	2.53 ± 0.22 μs	2.56 ± 0.22 μs	0.99
saxpy/static workgroup=(1024,)/Float16/65536	12.5 ± 0.29 μs	12.6 ± 0.52 μs	0.987
saxpy/static workgroup=(1024,)/Float32/1024	2.21 ± 0.033 μs	2.19 ± 0.033 μs	1.01
saxpy/static workgroup=(1024,)/Float32/1048576	0.244 ± 0.021 ms	0.255 ± 0.021 ms	0.957
saxpy/static workgroup=(1024,)/Float32/16384	4.33 ± 0.23 μs	4.35 ± 0.24 μs	0.995
saxpy/static workgroup=(1024,)/Float32/2048	2.36 ± 0.052 μs	2.36 ± 0.059 μs	0.999
saxpy/static workgroup=(1024,)/Float32/256	2.66 ± 0.04 μs	2.65 ± 0.058 μs	1
saxpy/static workgroup=(1024,)/Float32/262144	0.0605 ± 0.004 ms	0.0626 ± 0.0047 ms	0.966
saxpy/static workgroup=(1024,)/Float32/32768	7.4 ± 0.41 μs	7.48 ± 0.53 μs	0.99
saxpy/static workgroup=(1024,)/Float32/4096	2.65 ± 0.078 μs	2.66 ± 0.089 μs	0.998
saxpy/static workgroup=(1024,)/Float32/512	2.71 ± 0.087 μs	2.7 ± 0.079 μs	1
saxpy/static workgroup=(1024,)/Float32/64	2.69 ± 5.3 μs	2.68 ± 4.9 μs	1
saxpy/static workgroup=(1024,)/Float32/65536	15.2 ± 0.94 μs	16 ± 1.5 μs	0.946
saxpy/static workgroup=(1024,)/Float64/1024	2.31 ± 0.056 μs	2.34 ± 0.052 μs	0.984
saxpy/static workgroup=(1024,)/Float64/1048576	0.536 ± 0.052 ms	0.577 ± 0.058 ms	0.929
saxpy/static workgroup=(1024,)/Float64/16384	7.28 ± 0.4 μs	7.45 ± 0.62 μs	0.977
saxpy/static workgroup=(1024,)/Float64/2048	2.6 ± 0.082 μs	2.63 ± 0.087 μs	0.991
saxpy/static workgroup=(1024,)/Float64/256	2.65 ± 0.076 μs	2.69 ± 0.073 μs	0.983
saxpy/static workgroup=(1024,)/Float64/262144	0.117 ± 0.011 ms	0.124 ± 0.011 ms	0.944
saxpy/static workgroup=(1024,)/Float64/32768	15.4 ± 1.3 μs	15.9 ± 1.4 μs	0.97
saxpy/static workgroup=(1024,)/Float64/4096	3.14 ± 0.19 μs	3.21 ± 0.24 μs	0.978
saxpy/static workgroup=(1024,)/Float64/512	2.63 ± 0.054 μs	2.67 ± 0.062 μs	0.985
saxpy/static workgroup=(1024,)/Float64/64	2.58 ± 0.069 μs	2.65 ± 18 μs	0.971
saxpy/static workgroup=(1024,)/Float64/65536	31.2 ± 1.9 μs	0.033 ± 0.003 ms	0.947
time_to_load	0.322 ± 0.003 s	1.16 ± 0.0044 s	0.277

Benchmark Plots

A plot of the benchmark results have been uploaded as an artifact to the workflow run for this PR.
Go to "Actions"->"Benchmark a pull request"->[the most recent run]->"Artifacts" (at the bottom).

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 855 lines in your changes missing coverage. Please review.

Project coverage is 0.00%. Comparing base (8a87f77) to head (2121d5c).

Files with missing lines	Patch %	Lines
src/pocl/nanoOpenCL.jl	0.00%	497 Missing ⚠️
src/pocl/device/array.jl	0.00%	101 Missing ⚠️
src/pocl/backend.jl	0.00%	92 Missing ⚠️
src/pocl/compiler/execution.jl	0.00%	43 Missing ⚠️
src/pocl/compiler/compilation.jl	0.00%	32 Missing ⚠️
src/pocl/device/quirks.jl	0.00%	31 Missing ⚠️
src/pocl/compiler/reflection.jl	0.00%	23 Missing ⚠️
src/pocl/pocl.jl	0.00%	20 Missing ⚠️
src/macros.jl	0.00%	8 Missing ⚠️
src/pocl/device/runtime.jl	0.00%	6 Missing ⚠️
... and 1 more

Additional details and impacted files

@@          Coverage Diff           @@
##            main    #556    +/-   ##
======================================
  Coverage   0.00%   0.00%            
======================================
  Files         12      21     +9     
  Lines        777    1575   +798     
======================================
- Misses       777    1575   +798     

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